Question

Further studies on the snails with colored and patterned shells revealed a subset of individuals also had a wavy edge as opposed to a smooth shell. Consider a cross between:

•Parent 1: C/C ; w/w - Solid colored shell with a wavy border

•Parent 2: c/c ; W/W - Patterned shell with a straight border

a. Predict the genotypes and phenotypes of four offspring resulting from a cross between these individuals.

b. Describe the molecular reason(s) for how this phenotype results from this F1 genotype.

c. The F1 individuals are kept together and an F2 generation of progeny results. Predict the genotypes and phenotypes of 64 progeny individuals, assuming independent assortment.

Also, could you please give explanation. thank you so much.

Answer 1

a)Given that genotype of parent 1 is CCww and that of parent 2 is ccWW.

Cross between CCww and ccWW

Gametes produced are Cw from parent 1 and cW from parent 2

Punnet square

	Cw	Cw
cW	CcWw	CcWw
cW	CcWw	CcWw

There are four CcWw(solid colored shell with straight border) progenies in F1.

b)Here C and W are the dominant alleles and c and w are the recessive alleles.C produces solid colored shell and W produces a straight border.We should know about what is dominancy and recessiveness of alleles.Each individual has two alleles of a gene.Genes carry information about a particular trait.If one allele produces a defective/less efficient protein the corresponding phenotype will change.The other allele produces a normal,functioning protein.The functioning allele is called dominant allele and the other is called recessive allele.Homozygous and heterozygous dominant individual show dominant phenotype while homozygous recessive show recessive phenotype.

c)Cross between two F1 progenies CcWw and CcWw

Gametes produced are CW,Cw,cW and cw from both parents

Punnet square to find F2

	CW	Cw	cW	cw
CW	CCWW	CCWw	CcWW	CcWw
Cw	CCWw	CCww	CcWw	Ccww
cW	CcWW	CcWw	ccWW	ccWw
cw	CcWw	Ccww	ccWw	ccww

CCWW-solid color with straight border(1/16)

CCww-solid color with wavy border(1/16)

ccWW-patterned with straight border(1/16)

ccww-patterned with wavy border(1/16)

CcWw-solid color with straight border(4/16)

CCWw-solid color with straight border(2/16)

CcWW-solid color with straight border(2/16)

Ccww-solid color with wavy border(2/16)

ccWw-patterned with straight border(2/16)

64 individuals are produced from 4 such crosses.